Hydrocarbon recovery is a process by which hydrocarbons are extracted from a subterranean region (e.g., a region from which heavy viscous oil or other hydrocarbons can be extracted, or other types of regions). Hydrocarbon recovery can include primary recovery, secondary recovery, and tertiary recovery (also referred to as enhanced oil recovery (EOR)). EOR generally includes techniques for increasing the amount of hydrocarbon production by altering a reservoir's rock properties and/or the in-situ fluid properties to mobilize the trapped oil in the subterranean region.
Water flood is an example secondary recovery method performed before EOR implementations, in which water is injected into the reservoir formation to displace residual oil. Water flood and primary recovery combined typically recover about 50% of the oil in place. This number is even lower in fractured reservoirs that account for more than 20% of the world's hydrocarbon reserves. Water injection can be problematic in fractured reservoirs because injectant selectively channels through fractures toward producers, leaving much oil behind in the matrix. Recovering retained oil requires advanced engineering and injecting sophisticated fluids to drive oil toward producers. Some main recovery mechanisms rely either on increasing the flow resistance of injectants in high-permeability fractures or improving the imbibition process in the matrix-fracture system.